Please be sure you have installed and activated PRO version.
To install PRO version of plugin by Supsystic follow the next steps:
1. Install and activate the latest Free version of the plugin.
2. Download zip archive with PRO version from your personal account on the supsystic.com – you will find a unique download link after purchase.
3. Navigate to Plugins > Add New > Upload.
4. Upload the archive.
5. When the installation has completed, click “Activate Plugin”.
6. After activation of the PRO version, you need to enter license key (you can find it in your personal account on our site). To do this follow the next steps:
7. Go to the plugin in WordPress navigation menu.
8. Click License tab on the left navigation menu of plugin.
9. Enter your email and license key.
10. Click “Activate” button.

If the problem still persists, contact us through ourinternal support.
We will help you to solve the problem.

Something might went wrong, while you were installing the pro version at the first time.
So try to delete popup-by-supsystic-pro folder via FTP
and repeat your actions accordingly to previous instructions.